The present invention relates to a semiconductor device and more particularly to a technique effectively applicable to packaging of semiconductor devices.
Semiconductor devices of elemental structure for use as switches in power supply-related items including power amplifiers and power source units are available-in various package structures. For instance xe2x80x9c2.5 V-Driven Type 3rd Generation Trench Gate MOSFETxe2x80x9d in Toshiba Review , Vol. 53 , No. 11 (1998), pp.45-47 , describes a semiconductor device for power supply use of a package structure known as TSSOP (Thin Shrink small Out-line Package) type. In this TSSOP type semiconductor device, as a switching element, for instance, a semiconductor chip with a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) built into it is sealed with a resin sealing body.
On the other hand, the Japanese Published Unexamined Patent Application No. Hei 7-58293 (1995) (the counterpart of the U.S. Pat. No. 5,642,252) discloses a circuit system for controlling the turning on/off of a power MOSFET built into a semiconductor chip that is controlled with a controller.
Further, the Japanese Published Unexamined Patent Application No. Hei 5(1993)-234495 discloses a semiconductor device for power supply use in which a semiconductor chip with a built-in power MOSFET and a fuse element whose fusible portion is fused by its own heat when an overcurrent flows are sealed by a single resin sealing body. The fuse element is provided to prevent trouble from occurring when the source and drain of the power MOSFET are short-circuited to each other, and is connected to the power MOSFET in series.
Incidentally, the present inventors developed a semiconductor device (module) semiconductor chip with a built-in control circuit (hereinafter to be referred to simply as a xe2x80x9ccontrol chipxe2x80x9d), a plurality of semiconductor chips (hereinafter to be referred to simply as xe2x80x9cswitching chipsxe2x80x9d) each with a power MOSFET, as switching elements whose turning on/off is controlled by the control chip, and a plurality of fuse elements individually connected by these switching chips are sealed by a single resin sealing body. During their work to develop this semiconductor device, the present inventors discovered the following problems.
(1) As the amperage handled by the switching chips is high, the quantity of heat generated is high relative to that generated by the control chip. Therefore, where the plurality of switching chips are to be sealed with the control chip by the single resin sealing body, the chip arrangement should be such that heat generated by these chips can be efficiently discharged out of the resin sealing body.
(2) Where the control chip and the switching chips are to be electrically connected by bonding wires, the bonding wires should be kept as short as practicable. If the bonding wires are too long, the hanging portions of wire loops, after they have bonded the chips, are apt to invite short circuiting, and this would result in a low yield of the manufacturing process. Longer bonding wires would also invite a low yield of the manufacturing process in another way because, when resin sealing body is formed by a transfer mold process, a wire flow due to the fluidity of resin pressure-injected into the cavity of the molding die is apt to lead to short circuiting. However, depending on how the chips are arranged, some switching chips may far more distant from the control chip than other switching chips, and bonding wires for these distant switching chips become extremely long.
(3) For fuse elements whose fusible portions are fused by their own heat when an overcurrent flows, it is essential to secure stable fusing currents (breaking currents). However, where the fuse elements are sealed together with switching chips generating large quantities of heat by a single resin sealing body, the heat generated by the switching chips are transmitted via the resin of the resin sealing body to the fuse elements to destabilize the fusing currents of the fuse elements. Moreover, as the heat generated by the fuse elements escapes via the resin of the resin sealing body, the fusing currents of the fuse elements are destabilized in this respect as well. Then, selective providing hollows in the fuse element part to prevent the elements from getting in contact with the resin of the resin sealing body could restrain the effect of heat transmitted via the resin of the resin sealing body and that of heat escaping via the resin of the resin sealing body, and this contributes to stabilizing the fusing currents of the fuse elements, but it is difficult to selective form hollows in the fuse element part by the transfer mold method which is suitable for mass production.
Furthermore, for a semiconductor device requiring high heat radiation, a heat radiation plate (cooling wheel) is selected. In a package structure having a heat radiating plate, as heat generated by switching chips is more easily transmitted to fuse elements and heat generated by the fuse elements can more easily escape, the fusing currents of the fuse elements become even more unstable.
An object of the present invention, therefore, is to provide a technique capable of helping improve heat radiation from semiconductor devices.
Another object of the invention is to provide a technique capable of helping enhance the yield in semiconductor device manufacturing.
Still another object of the invention is to provide a technique capable of helping stabilize the stability of the fusing currents of fuse elements.
These and other objects and novel features of the invention will become apparent from the following description of the specification when taken in conjunction with the accompanying drawings.
Typical aspects of the invention disclosed in this application will be briefly outlined below.
(1) A semiconductor device comprising:
a first semiconductor chip having a control circuit,
a plurality of second semiconductor chips each having a switching element, and
a resin sealing body for sealing the first semiconductor chip and the plurality of second semiconductor chips, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body, and
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip.
(2) A semiconductor device comprising:
a first semiconductor chip having on one main surface a control circuit and a plurality of electrodes,
a plurality of second semiconductor chips each having on one main surface a switching element and an electrode,
a plurality of bonding wires for electrically connecting the plurality of electrodes of the first semiconductor chip and respective electrodes of the plurality of second semiconductor chips, and
a resin sealing body for sealing the first semiconductor chip, the plurality of second semiconductor chips and the plurality of bonding wires, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body, and
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip.
(3) The semiconductor device described in (1) or (2), wherein:
the plurality of second semiconductor chips are arranged symmetrically relative to the first semiconductor chip.
(4) A semiconductor device comprising:
a first semiconductor chip having a control circuit, a plurality of second semiconductor chips each having a switching element,
a plurality of fuse elements whose fusible portions are fused by their own heat when an overcurrent flows, and
a resin sealing body for sealing the first semiconductor chip, the plurality of second semiconductor chips and the plurality of fuse elements, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body,
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip, and
the plurality of fuse elements are arranged on a periphery of the first semiconductor chip and outside the second semiconductor chips.
(5) A semiconductor device comprising:
a first semiconductor chip having on one main surface a control circuit and a plurality of electrodes,
a plurality of second semiconductor chips each having on one main surface a fuse element and an electrode,
a plurality of fuse elements whose fusible portions are fused by their own heat when an overcurrent flows,
a plurality of bonding wires for electrically connecting the plurality of electrodes of the first semiconductor chip and respective electrodes of the plurality of second semiconductor chips, and
a resin sealing body for sealing the first semiconductor chip, the plurality of second semiconductor chips and the plurality of bonding wires, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body,
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip, and
the plurality of fuse elements are arranged on a periphery of the first semiconductor chip and outside the second semiconductor chips.
(6) The semiconductor device described in (4), wherein:
the plurality of second semiconductor chips are arranged symmetrically relative to the first semiconductor chip.
(7) A semiconductor device comprising:
a semiconductor chip having a switching element,
a fuse element whose fusible portion is fused by its own heat when an overcurrent flows, one end of the fuse element being connected to a first pad and the other end being connected to a second pad, and
a resin sealing body for sealing the semiconductor chip, the fuse element and the first and second pads, wherein:
the resin sealing body has, in a portion opposite to the fuse element, concave portions sinking from one main surface of the resin sealing body toward the fuse element.
(8) The semiconductor device described in (7), wherein:
the concave portions is formed in such a depth that from its bottom surface an intermediate portion of the fuse element is exposed.
(9) The semiconductor device described in (7), wherein:
the concave portions is formed in such a depth that between its bottom surface and the fuse element the resin of the resin sealing body intervenes.
(10) A semiconductor device comprising:
a semiconductor chip having a switching element,
a fuse element whose fusible portion is fused by its own
heat when an overcurrent flows, one end of the fuse element being connected to a first pad and the other end being connected to a second pad, and
a resin sealing body for sealing the semiconductor chip, the fuse element and the first and second pads, wherein:
an intermediate port of the fuse element is covered with a resin whose thermal conductivity is lower than that of the resin of the resin sealing body.
(11) A semiconductor device comprising:
a heat radiation plate having one main surface and another main surface opposite to each other and through holes continuous from the former main surface to the latter main surface,
a semiconductor chip having on one main surface a switching element and arranged on one main surface of the heat radiating plate,
a first pad and a second pad arranged on one main surface of the heat radiating plate,
a fuse element whose fusible portion is fused by its own heat when an overcurrent flows, one end of the fuse element being connected to the first pad and the other end being connected to the second pad, and
a resin sealing body for sealing the semiconductor chip, the first and second pads and the fuse element, resin sealing body being fixed to the heat radiating plate, wherein:
the through holes penetrating the heat radiation plate are arranged in a position opposite to the fuse element.
(12) The semiconductor device described in (11), wherein:
the resin sealing body has, in a portion opposite to the fuse element, a first concave portion sinking from one main surface of the resin sealing body opposite to one main surface of the semiconductor chip toward the fuse element and a second concave portion sinking from the other main surface opposite to one main surface of the resin sealing body through the through holes in the heat radiation plate toward the fuse element.
(13) The semiconductor device described in (12), wherein:
the first and second concave portions are formed in such a depth that from their bottom surfaces an intermediate portion of the fuse element is exposed.
(14) The semiconductor device described in (7), wherein:
the first and second concave portions are formed in such a depth that between their bottom surfaces and the fuse element the resin of the resin sealing body intervenes.